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BP: Fachverband Biologische Physik

BP 11: Cytoskeleton

BP 11.6: Vortrag

Dienstag, 18. März 2025, 11:00–11:15, H44

Keratin networks in epithelial cells under strain — •Ruben Haag, Ruth Meyer, and Sarah Köster — Institute for X-Ray Physics, University of Göttingen, Germany

The cytoskeleton is mainly made up of microtubules, actin and intermediate filaments (IFs). The composition of the IF-network is cell-type specific and influences the viscoelastic properties of cells. In epithelial cells, the keratin IF network connects to desmomes in the cell membrane, while in the cell center keratin IFs can bind to the nuclear lamina via plectin proteins. The keratin IF network thus forms a mechanical link from the nucleus to the cell membrane. In in-vitro experiments, it was previously observed that IFs, unlike actin filaments, resist being stretched to high strains. We now ask whether this force-extension behavior of IFs is also relevant in whole cells and, more specifically, if mechanical signals from outside the cell are transmitted to the nucleus via the keratin IF network. To answer this question, we stretch cells both uniaxially to linear strains of 80 % and equibiaxially to area strains of 87 %. During stretching, we image the nuclei, deconvolve the images to recover their 3D shape, segment the nuclei and track each nucleus during stretching. This procedure allows us to investigate their deformation at increasing strain. We compare wild type epithelial cells to keratin knockout cells to study the influence of the keratin IF network on the nuclei. We find that the deformation orthogonal to the stretching direction of the nuclei matches the deformation of the cell better in the keratin wild type cells. Our results suggest, that the keratin network helps to adapt the nucleus to mechanical perturbation.

Keywords: Keratin; Nucleus; Cell stretching; Actin